Field of the Invention
The present invention relates to radially compliant stent grafts that may be used to indicate a pressure differential across the wall of the radially compliant stent graft.
Background
Stents made out of super elastic materials, such as Nitinol, have been used to produce radially compliant stents. However, grafts made out of fluoropolymers, such as expanded PTFE, are not elastic. Stents and grafts are combined to produce self-expanding stent grafts that are radially compliant in compression only, as the graft is not elastic. The graft can be radially compressed but cannot be radially expanded as it will stretch and damage the graft material. Typically, a stent graft is constricted down in diameter and retained in this constricted state until positioned within the vasculature for deployment, where the stent graft is expanded radially within the vasculature. In most cases, the stent graft is oversized, wherein the stent graft diameter in a free state is larger than the diameter of the vasculature, thereby ensuring that the stent graft is retained in position. The stent graft is radially compliant only in compression and will expand radially only to the diameter of the non-elastic graft. In addition, the inability of conventional stent graft to radially comply with pulse pressure profiles can have deleterious cardiovascular effects, wherein the load of the heart is increased. In addition, a systolic pulse from the heart is not attenuated by non-compliant conventional stent grafts. There exists a need for a stent graft that is radially compliant in both expansion and compression, more like healthy native vascular tissue.